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sprinkles08
sprinkles08, ASE Certified Technician
Category: Jeep
Satisfied Customers: 21987
Experience:  Chrysler/Dodge/Jeep Master Certified, ASE Master and Advanced Certified, Trans and Hybrid Specialist
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I am working on a 2001 Jeep Grand Cherokee 4.7. THis one is

Customer Question

I am working on a 2001 Jeep Grand Cherokee 4.7. THis one is a real puzzler and I am missing something here. First quick history of this vehicle. Customer overheated engine so bad a valve seat dropped in right head. I removed the head and had it reconditioned at machine shop. After installing the head and running about half hour, I moved the vehicle to jack up and bolt down exhaust. When I did the engine started acting up and shutting off. If I accelerated with foot on brake, the ASD fuse would blow. Long story short...after blowing many 30 amp fuses trying to find short. I was short on fuses and put 50amp fuse in to get the customer back from taking it to another shop for diagnosis. I did eventually show up as a shorted ignition coil. However, it fried the PCM and needed replaced. Thinking for sure the coil and new PCM would fix the problem, same issue still exists. I installed a digital amp meter in the ASD fuse location. Start engine up and amperage is fine, 3 to 5 amps. Then if allowed to idle it will eventually shut off and restart every time. However, if I crack the throttle the slightest amount the amperage starts to spike over 30amps and engine will start misfiring one cylinder at a time and eventually shut down. PCM seems to go into an individual cylinder shutdown. Weird thing is if I hold the throttle just off idle and it starts acting up. If I unhook the TOS, it will run fine until I hook it back up. I can rev the engine and everything without misfire. I studied the schematic and as far as I can tell the only circuit without a lighter fuse down stream is the ignition coils. I have tried all sorts of elimination technics but come up with nothing yet. Any ideas concerning this very strange electrical issue? THanks!
Submitted: 3 months ago.
Category: Jeep
Customer: replied 3 months ago.
I see no edit price link but gladly will pay more for good answer
Expert:  sprinkles08 replied 3 months ago.

Hello and welcome to JustAnswer!

Current draw on the ASD circuit is climbing due to excessive ignition dwell because of incorrect cam timing, this is a common issue when one is reassembled incorrectly. You'll need to again remove the valve covers and timing cover and set cam timing correctly. There may just be an issue with the right secondary chain or the primary chain throwing the whole engine off; the left secondary may be incorrect also but is not monitored because the cam sensor is on the right bank.

Customer: replied 3 months ago.
I did replace the right chain when head was removed because tensioner was all the way extended. Could not replacing left chain as well cause this problem? I was pretty sure timing marks are correct. thanks!
Expert:  sprinkles08 replied 3 months ago.

Replacing the left secondary chain wouldn't cause this as that side is not monitored. Cam timing between the crankshaft and right camshaft is incorrect.

Customer: replied 3 months ago.
Ok..I will check it out! Thanks! Been a technician for 30 plus years and never heard of anything so crazy! Wonderful design...LOL
Expert:  sprinkles08 replied 3 months ago.

You're welcome and good luck with it!